SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56622408896143ab204874669b09734e332cf97e3ee97d7c436818d6247b88c4' 
  AND token = '+hlLPfjfoyZEm/4iT2KWiVP77zzohSGHqKb5NSTXFME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}